Applied Equipartition Theorems for the Design and Oprimization of Heat Exchanger Networks
The exergy losses of heat exchangers is caused by different forms of irreversibility due to: (i) Heat transfer over a finite temperature difference; (ii) Pressure losses;（iii) Thermal interaction with the environment;（iv) Stream-wise conduction in the walls of the heat exchanger. The exegy losses of each forms was analyzed. And then it deals with the optimal design or optimization of heat exchangers and develops the following theorem: for a given duty, the best configuration of the exchanger is that in which the exergy losses is most uniformly distributed. This principle is first analyzed in detail on the simple example of tubular heat exchangers, under the conditions of classical non--equilibrium thermodynamics: liner flux-force relations and Onsager’s reciprocity relations. A main result is established, which states that the total exergy losses is minimal when the local losses is uniformly distributed (equipartition). Then relate the exergy losses and the variance of the distribution to economic factors such as the duty, the exchanger area, the fluid flow-rates, and the temperature changes. Furthermore，the equipartition theorems is extended to multi-stream heat exchangers, heat exchanger networks(HEN) and then multi-stream heat exchanger networks(MSHEN). Finally a generalization of the equipartition is proposed. For heat transfer processes, the exergy losses is uniformaly distributed over the system, and reduces to equipartition of exergy losses when the cost factors are constant over the whole system. Examples illuminated the applying of equipartition theorems is significant for the design and optimization of heat exchanger networks.
Equipartition Theorems Exergy Losses Multi-Stream Heat Exchangers Heat Exchanger Networks
WANG ShaoMin KUANG GuoZhu YAO PingJing
Department of Chemical Engineering,Dalian University of Technology,Dalian,116012,China
国际会议
西安
英文
2007-08-15（万方平台首次上网日期，不代表论文的发表时间）